Page 79 - Impiantistica Industriale - Settembre Ottobre 2014
P. 79
conventional steam cycle using low cost fuels maximum grid required load
as coal or extra heavy hydrocarbon; In this case a portion of the kWh produced must
be stored and used when renewable power is not
• super-safe nuclear; available. This could be a chance for the owners of
• combined cycle with natural gas; EES (Electricity Energy Storage) to obtain financial
• renewables; return from EES investments. Utilities can reduce
• large energy storage and smaller energy total generation costs by eliminating power plants
working only during load peak periods, though the
storage connected to distribution grids. use of stored electricity generated by renewables.
Unfortunately there is always somebody against Renewables sources power capacity
every option and it is difficult to keep the debate equivalent to the maximum grid load
at a reasonable level. In any case 10 km2 of wind In this case an high portion of the kWh produced
mills cannot replace a base load plant because it is must be stored and used when renewables power
still needed the coal or nuclear station somewhere is not available.
just in case the wind stopped, if adequate energy
storage has not been planned. In the third case the Authorities could set up the
Being the renewable units mainly connected to the grid control through the following actions [13, 14]:
distribution grids, it is evident that the management • retrofit of distribution and transmission grids
of the electrical system is changing and renewable
energy could be transferred from one area to and set up energy storages within distribution
another also back through transmission lines. networks nearby to the consumption
We could envisage the following different cases. barycenter;
• improve fossil power generation units flexibility
including their ability to daily cycling;
• improve fossil units load change rate to higher
value (about 8%/min) and combining this
modification with steam turbine manufacturers;
• reduce once through coal fired boiler minimum
load to 10-15% from present 35%.
Electricity management before the Being the capital cost and O&M (Operation &
development of renewables Maintenance) of the energy storages high, the
During peak periods (consumption higher than improvement of flexibility and availability also to
average load), power suppliers complement the daily cycling of existing and new fossil power
power output of the base-load power plants generation units could be the alternative of the
(such as coal fired and nuclear units, but also high increase of energy storages.
efficiency combined cycle units) with flexible power In the fourth case power generation is totally
generation plants. During the off-peak period, supplied by renewables and integration from other
when less electricity is consumed, costly types of generation sources will be not required.
generation can be stopped. Authorities must define what is the most competitive
case for their network, comparing the costs of the
Renewables sources power capacity lower of different solutions.
the minimum grid load
In this case all the kWh produced by renewables 2.1 Doing its best to minimize the
are always transferred to the users, no renewables environmental impact
power must be stored and the management is
similar the that of the first case. Usually an electric company designs its plants
according to the existing regulations, but this policy
Renewables sources power capacity higher could be full of risks, because authorities can move
of the minimum grid load, but lower of the to tighter regulations, pushing the company to
costly plant modifications.
The increase of renewables and in some country of
shale gas is making more complex set up actions
to minimize the environmental impact.
Companies must take also into account present
or future costs to modify their plants in case of
regulations modifications and to mitigate the external
costs due to the pollution damages produced
by their plants. These costs of the environmental
effects are also known as externalities.
78 Impiantistica Italiana - Settembre - Ottobre 2014
as coal or extra heavy hydrocarbon; In this case a portion of the kWh produced must
be stored and used when renewable power is not
• super-safe nuclear; available. This could be a chance for the owners of
• combined cycle with natural gas; EES (Electricity Energy Storage) to obtain financial
• renewables; return from EES investments. Utilities can reduce
• large energy storage and smaller energy total generation costs by eliminating power plants
working only during load peak periods, though the
storage connected to distribution grids. use of stored electricity generated by renewables.
Unfortunately there is always somebody against Renewables sources power capacity
every option and it is difficult to keep the debate equivalent to the maximum grid load
at a reasonable level. In any case 10 km2 of wind In this case an high portion of the kWh produced
mills cannot replace a base load plant because it is must be stored and used when renewables power
still needed the coal or nuclear station somewhere is not available.
just in case the wind stopped, if adequate energy
storage has not been planned. In the third case the Authorities could set up the
Being the renewable units mainly connected to the grid control through the following actions [13, 14]:
distribution grids, it is evident that the management • retrofit of distribution and transmission grids
of the electrical system is changing and renewable
energy could be transferred from one area to and set up energy storages within distribution
another also back through transmission lines. networks nearby to the consumption
We could envisage the following different cases. barycenter;
• improve fossil power generation units flexibility
including their ability to daily cycling;
• improve fossil units load change rate to higher
value (about 8%/min) and combining this
modification with steam turbine manufacturers;
• reduce once through coal fired boiler minimum
load to 10-15% from present 35%.
Electricity management before the Being the capital cost and O&M (Operation &
development of renewables Maintenance) of the energy storages high, the
During peak periods (consumption higher than improvement of flexibility and availability also to
average load), power suppliers complement the daily cycling of existing and new fossil power
power output of the base-load power plants generation units could be the alternative of the
(such as coal fired and nuclear units, but also high increase of energy storages.
efficiency combined cycle units) with flexible power In the fourth case power generation is totally
generation plants. During the off-peak period, supplied by renewables and integration from other
when less electricity is consumed, costly types of generation sources will be not required.
generation can be stopped. Authorities must define what is the most competitive
case for their network, comparing the costs of the
Renewables sources power capacity lower of different solutions.
the minimum grid load
In this case all the kWh produced by renewables 2.1 Doing its best to minimize the
are always transferred to the users, no renewables environmental impact
power must be stored and the management is
similar the that of the first case. Usually an electric company designs its plants
according to the existing regulations, but this policy
Renewables sources power capacity higher could be full of risks, because authorities can move
of the minimum grid load, but lower of the to tighter regulations, pushing the company to
costly plant modifications.
The increase of renewables and in some country of
shale gas is making more complex set up actions
to minimize the environmental impact.
Companies must take also into account present
or future costs to modify their plants in case of
regulations modifications and to mitigate the external
costs due to the pollution damages produced
by their plants. These costs of the environmental
effects are also known as externalities.
78 Impiantistica Italiana - Settembre - Ottobre 2014
